remove http hop headers (easegress-io#650)

pkg/filter/proxy/pool.go

@@ -195,6 +195,10 @@ func (p *pool) handle(ctx context.HTTPContext, reqBody io.Reader, client *Client
  setStatusCode(http.StatusServiceUnavailable)
  return resultServerError
  }
+ removeConnectionHeaders(resp.Header)
+ for _, h := range hopHeaders {
+ resp.Header.Del(h)
+ }
 
  addLazyTag("code", "", resp.StatusCode)
 

pkg/filter/proxy/request.go

@@ -22,11 +22,14 @@ import (
  "fmt"
  "io"
  "net/http"
+ "net/textproto"
  "strconv"
+ "strings"
  "sync"
  "time"
 
  httpstat "github.com/tcnksm/go-httpstat"
+ "golang.org/x/net/http/httpguts"
 
  "github.com/megaease/easegress/pkg/context"
  "github.com/megaease/easegress/pkg/logger"
@@ -49,6 +52,49 @@ type (
  }
 )
 
+// removeConnectionHeaders removes hop-by-hop headers listed in the "Connection" header of h.
+// See RFC 7230, section 6.1
+func removeConnectionHeaders(h http.Header) {
+ for _, f := range h["Connection"] {
+ for _, sf := range strings.Split(f, ",") {
+ if sf = textproto.TrimString(sf); sf != "" {
+ h.Del(sf)
+ }
+ }
+ }
+}
+
+// https://github.com/golang/go/blob/95b68e1e02fa713719f02f6c59fb1532bd05e824/src/net/http/httputil/reverseproxy.go#L171-L186
+// Hop-by-hop headers. These are removed when sent to the backend.
+// As of RFC 7230, hop-by-hop headers are required to appear in the
+// Connection header field. These are the headers defined by the
+// obsoleted RFC 2616 (section 13.5.1) and are used for backward
+// compatibility.
+var hopHeaders = []string{
+ "Connection",
+ "Proxy-Connection", // non-standard but still sent by libcurl and rejected by e.g. google
+ "Keep-Alive",
+ "Proxy-Authenticate",
+ "Proxy-Authorization",
+ "Te", // canonicalized version of "TE"
+ "Trailer", // not Trailers per URL above; https://www.rfc-editor.org/errata_search.php?eid=4522
+ "Transfer-Encoding",
+ "Upgrade",
+}
+
+// info: https://github.com/golang/go/blob/95b68e1e02fa713719f02f6c59fb1532bd05e824/src/net/http/httputil/reverseproxy.go#L214
+func processHopHeaders(inReq, outReq *http.Request) {
+ removeConnectionHeaders(outReq.Header)
+
+ for _, h := range hopHeaders {
+ outReq.Header.Del(h)
+ }
+
+ if httpguts.HeaderValuesContainsToken(inReq.Header["Te"], "trailers") {
+ outReq.Header.Set("Te", "trailers")
+ }
+}
+
 func (p *pool) newRequest(
  ctx context.HTTPContext,
  server *Server,
@@ -76,7 +122,7 @@ func (p *pool) newRequest(
  return nil, fmt.Errorf("BUG: new request failed: %v", err)
  }
 
- stdr.Header = r.Header().Std()
+ stdr.Header = r.Header().Std().Clone()
  // only set host when server address is not host name OR server is explicitly told to keep the host of the request.
  if !server.addrIsHostName || server.KeepHost {
  stdr.Host = r.Host()
@@ -89,6 +135,7 @@ func (p *pool) newRequest(
  stdr.ContentLength = int64(l)
  }
  }
+ processHopHeaders(r.Std(), stdr)
 
  req.std = stdr